ASP.NET(C#)验证数字的两种方法

int i=0;
if (!int.TryParse(this.txtPage.Text, out i))
{
   Response.Write("<script>alert('请输入有效数字！')</script>");
   this.txtPage.Text = string.Empty;
 }//判断是否是数字

try
        {

 

            if (Convert.ToInt32(this.txtPage.Text) > totalPage || Convert.ToInt32(this.txtPage.Text)<1)
            {
                ClientScript.RegisterClientScriptBlock(GetType(), "提示", "alert('请输入有效数字！')", true);
            }
            else
            {
              ViewState["pageindex"] = this.txtPage.Text;
              GetData();
            }
        }
        catch (Exception)
        {
           ClientScript.RegisterClientScriptBlock(GetType(), "提示", "alert('请输入有效数字！')", true);
        }